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Inflammatory Bowel Diseases: When Your Gut Self-Destructs


Is there anything worse than having diarrhea and abdominal pain during a social event? Unfortunately, there are many worse options, and one of them is due to an autoimmune response. If this occurs, we may be facing an Inflammatory Bowel Disease or IBD.

IBDs consist of chronic inflammation of the intestine because the immune system itself acts anomalously and aggressively, causing damage to cells and tissues. However, this situation is usually not due to an attack against the body itself, despite being called autoimmune diseases, but rather an activation against bacterial antigens.

These are complex genetic diseases, with a strong environmental component and related to the intestinal microbiota, which have been increasing in frequency in recent years. How complex? So complex that 200 DNA regions related to IBDs have been identified, encompassing more than 300 genes that are potential candidates. At the same time, with so many actors participating in the same play, each of the genes individually tends to have a low influence on the disease.

They are chronic, so although the symptoms can be treated and those affected can lead a normal life, these diseases have no cure. They accompany you forever. Stages of calm can be followed by stages with a strong relapse. Currently, the International Inflammatory Bowel Disease Genetics Consortium (IIBDGC) has data with the sequencing of the genome of more than 75,000 patients with the disease, with the aim of studying the interactions between genetic and non-genetic risk factors and their link to the development of the diseases.

The two most well-known IBDs are ulcerative colitis and Crohn’s disease, although they are not the only ones. Between the two, in 2019 there were 4.9 million cases worldwide. However, there are many other subtypes, sometimes indistinguishable in their phenotype, but with different genetic risks and responses to treatment. In the developed world, they are more frequent due to diet, lifestyle, and lower exposure to intestinal infections in these regions of the world. Literally, first-world problems.

enfermedades inflamatorias intestinales

Genetics and Ulcerative Colitis, It Could Be Worse

Ulcerative colitis affects the colon and rectum, with abdominal pain and diarrhea accompanied by blood as basic symptoms. The originally damaged area usually arises in the rectum and then spreads throughout the colon. This inflamed region is only at the level of the inner lining of the large intestine without reaching the deeper layers of the tissue.

It is a disease described as early as 1850. The test for colitis is performed through an endoscopy with tissue biopsy.

Among the treatments, dietary changes (such as the elimination of lactose) and the use of various drugs are recommended. In severe cases with no improvement with the previous procedures, surgical removal of the colon may be necessary, a definitive solution with high success. If the disease occurs in an organ and you remove it, it makes sense that the disease goes with it.

Genetics and Crohn’s Disease, It’s Worse

Crohn’s disease is more ambitious and can affect any region of the gastrointestinal tract, from the mouth to the rectum, yes, even the mouth, although it seems to have a preference for the terminal ileum area. Unlike colitis, the damaged area is not continuous, but patches of affected tissue surrounded by healthy tissue emerge. In addition, all layers of the intestinal wall can be inflamed, and there is a higher risk of deforming the structure.

Its symptoms have a greater variety. In addition to diarrhea and abdominal pain, there are fever, abdominal distension, and weight loss. It is also more common to have symptoms external to the digestive system, such as anemia or skin rashes, compared to colitis that occurs less frequently. The test for Crohn’s disease is once again an intestinal endoscopy, which allows ruling out other diseases with similar symptoms.

Treatments include the use of drugs, for smokers to quit smoking, and sometimes surgery to remove abscesses and tumors. However, as it is not located in a specific tissue, it is not a permanent solution.

It was precisely in Crohn’s disease that the first gene related to IBDs, the NOD2 gene, was discovered. At tellmeGen, it is one of the genes we study to check for predisposition. It has been linked to the genetics of IBDs as a whole, including the genetics of ulcerative colitis.

Inflammatory Bowel Diseases That Are Not Popular

Sometimes a third type of IBD is considered, indeterminate colitis, cases that share features with the two previous ones or even have other different features, and cannot be classified into them. When in science you don’t know where to put something, you create the “I Don’t Know” box and put it there.

Finally, we have microscopic colitis, typical in older people. In this case, there is no blood in the stools (although there is diarrhea), and in a visual examination, the tissue does not show inflammation, although it can be detected through biopsies. Like the previous ones, it is chronic, but it has a positive prognosis. It won’t kill you.

We have it in two colors. Lymphocytic colitis, characterized by a high number of lymphocytes in the tissue, and collagenous colitis, which has a thick band of collagen under the epithelium of the mucosa (and also an increased number of lymphocytes).

An additional problem with IBDs is that the constant presence of an inflammatory state is a high risk for the development of colorectal cancer, mainly in ulcerative colitis. In contrast, Crohn’s disease increases the risk of cancer in inflamed areas throughout the gastrointestinal tract.

To diagnose colon cancer, the most reliable method is colonoscopy and tissue biopsy. After 8-10 years of suffering from the disease, it is recommended to have colonoscopies every 1-2 years and biopsies of any dysplasia found in the process. Other techniques help, such as searching for biomarkers in the blood or studies of colon cancer genetics.

Genetic tests are a great help if you want to delve into your predisposition to these and other diseases. At tellmeGen, the Advanced DNA Kit is an option you have at your disposal.


Carlos Manuel Cuesta

Graduate in Biology. PhD in Biotechnology

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